Automatic train control system



Feb. 2, BODDE AUTOMATIC TRAIN CONTROL SYSTEM Filed May 16,1929

ATTORNEY VEN OR M M, BY

E0 skmok 33 nzml Patented Feb. 2, 1932) p Prat oFFmE 'rnnono-nn BODDE,or nocnnsrnn ivnvr Yonir, nssrenon T GENERAL RAILWAY,

' srenenoomrnmr, or ROCHESTER, NEW YORK 'Anirorrnrrc *rnnnsr comm:SYSTEM "Application filed ne ieg 1929. Serial No. 383,531.

This invention relates to automatictrain control systems, and moreparticularly to train control systems of the, shoe and ramp" type.

In applying automatic train control to existing railway signallingsystems, it is desired to communicate automatically, from the trackwayto the movin'gvehicle, the conditions oftrafiic existing ahead of suchveof the rectifier may be determined on the C213 hicle. dlstant signalindications are used,. or

whether three indication condition type signalsare used,.in which clear,caution, and danger are indicated to the engineer of the train, it isdesirable to manifest on the car at least three kinds of traflicconditions, conventionally called clear or proceed, caution and dangeror stop traffic conditions. In

order to transmit a plurality of distinctive control influences from a's1ngle ramp to a moving railway vehicle, it is necessary to make theramp distinctive under the various conditions of trattic. v

In accordance with the present invention it is proposed'that thepresence ofthel ramp itself be manifestedon the-car by lifting. a

shoe located on that car, and to givethe' ramp two other distinctivecharacteristics by connecting a rectifier between such ramp, and thetrack rails, so that through the m'edium of contact between acar-carried shoe and the ramp the direction of. valve action Morespecifically, it is proposed in accordance with the present invention toemploy a polyphase induction-type relay on the railway vehicle, havingtwo windings connected in multiple branches and each winding including arectifier, in series therewith, these rectifiers having their valveaction poled oppositely, and having these multiple branches Irrespectiveof whether home and beenillustrated as a semaphore signal having theusual &5 degree and 90' degree circults,

sounded during each passage of the carcarrled equipment over a clear orproceed ramp, the provision of means to effect a.

I brake application'that may be easily lan- 'nulled-hy-the engineer uponthe passage over a caution ramp and the provision of means to cause vthebrakes to be applied, in such a-v manner that they cannot be easilyreleased, upon passage of the vehicle by a stop ramp; 'Gther objects,purposes and characteristic features of the invention will appear inpart as the description thereof progresses, andwill in part b'e obviousfrom the accompanying drawing. i In describing the'invention in detail,reference will be made to the single accompanying drawing in which oneembodiment of the present invention has been illustrated. Track wayapparatua lteferring particularly to the trackway apparatus, the rails 1of a double track railway system, in whichtraflic normally moves fromleft'to' right in the direction of the arrow, is divided byinsulating'jointsQ intO blocks of which the block I and the adjacentends of two other blocks and J only have'been'illustrated. At theentrance to each" block is provided a suitable signal Z, having adistinctive ex ponent, which signal for convenience has which circuitsfor "the signalsZ and'Z are energized from the batteries 4: and 4:through contacts of the polar track relays T and T There is alsoprovided at each signal location arepeater relay RE, which isenergizedonly when the corresponding track relay T is energized to its right handclear position; this repeaterrelay RR through its contacts 6 and 7 polechanges the rectifier 8 in accordance with the 'energization of therepeaterrelay RR, this rectifier 8 being connected between the trackrails 1 and the track-ramp TR through the medium of a semaphore contact"9 and a track relay contact 10. This semaphore contact is operativelyconnected to the semaphore signal blade by suitable means conventionallyshown bythe dotted line' l l. From thisconstruction of the trackwayapparatus, it appears that under clear traflic tive polarity from thetrackbattery 11 tov the track rails of the block I, and thereby causingthe track relay T to assume its left hand energized position effectingde-energization of the repeater relay RR and movement of the signal Z tothe caution position, whereby the rectifier 8 will be connected in acircuit to permit the flow of direct current from the ramp TR to thetrack rails 1..

It is thus seen, that the pole-changer contacts 12 and 12 assume theirnormal positive polarity position through the medium of an operativeconnection indicated by dotted lines 13 and 13 when the correspondingsignal assumes the clear or caution position, but this pole-changerassumes the negative position when such signal assumes the stop position. Further, it is obvious that with the track relay T deenergized, asis the case when the block I is occupied, the track ramp TR will bedisconnected from the track 1 through the medium of the contact 10 ofthe track relay T, and also under this condition of traffic thesemaphore contact 9 will break theramp circuit.

Oar-carried apparat'us.-On the railway vehicle is carried a shoe 20adapted to contact with a trackway ramp TR, TR etc. during the passageof the car by a signal location. This shoe 20 not only contacts withthese ramps TR, but also is raised during such con tact with the trackramps, thereby opening the contacts 21 and 22 and closing. the con--tacts 23 and 2st. The car-carried equipment also includes aturbo-generator G, adapted to generate direct current, as conventionallyillustrated by commutator 25, and to generate alternating current asillustrated by the slip rings 26, which slip rings 26 are connected to atransformer 27. The car-carried apparatus also includes a main relay MBof the polyphase inductive type, and two neutral stick relays CA and CLfor manifesting clear and caution traffic conditions, respectively, andfurther includes a slow-dropping signal relay SR, audible signals BL andWV, and a suitable normally energized brake control device EPV.

Attention is directed to the fact that the windings 30 and 31 of thetwo-element inductive type relay MR are connected in multiple, that thewinding 30 has connected in nected oppositely in these two branchcircuits, the purpose for which will be described hereinafter. Thecar-carried apparatus also includes an annulling push button AN, and areset push button RS. It is believed that the construction as well asthe operating characteristics of the system are most readily explainedby considering the operation of the system.

Operation.-Under normal clear traffic conditions of the car-carriedapparatus, that is, when the railway vehicle 35 is moving along therailway track between the ramps when such vehicle has just passed aclear ramp, namely, when the railway vehicle is moving in a clear block,the caution relay CA and the clear relay'CL are respectively energizedthrough the following stick circuits:(1) beginning at the plus bus wire7 36, contacts 21-, wires 37 38, and 39, stick contact 40' ofthe relayCA, wires 41 and 42. lower winding. of. the relay CA, wires 43 and 44,to the minus bus; and (2) beginning at the plus bus, wire 36, contacts21, Wires 37, 38, 46, and47, stick contact 48 of the clear relay CL,wire 49 and 50, lower winding of the glear relay CL, wire 51, and 44, tothe minus With the relays CA and CL both energized the electro-pneumaticbrake control device EPV is energized through the followingcircuit:beginning at the plus bus, wires 52 and 53, contact 5% of thereset push button RS, wires 55 and 56, contacts 22 of the shoe 20, wire57, contact 58 of the caution relay CA, wire 59, contact 60 of the clearrelay CL, wires 61 and 62, normally closed contact 63 of the annullingpush button AN, wire 64, windingofthe electropneumatic valve EPV, wire65 to the negative bus. It is thus seen that the electro-pneumatic valveis maintained energizedunder the conditions stated, thereby holdingsuitable pneumatic operated brake control apparatus in its inactivecondition, said valve if de-energized causing an automatic applicationof the brakes of the railway vehicle.

Let us now assume that the railway vehicle represented by the wheels andaXle 35 passes a caution ramp. As the shoe 20 engages the track ramp TR-it opens the shoe contacts 21 and 22 and closes the shoe con tacts 23and 24:. It may be pointed out here, that the contacts 2123, as well ascontacts 2224 are preferably makebefore-break contacts,that is, contacts23 and 2a are closed before contacts 21 and 22 are opened, and viceversa. l/Vith the shoe contacts 22 opened and shoe contacts 2a closed,the electro-pneumatic valve EPV is maintained energized through thefollowing circuit :beginning at the plus bus, wires 52land53, contact 54of the reset push button BS, wires 55 and 66, shoe contacts 24, wires 67and 62, dash pot retardedv contacts 63 of the annulling push button AN,wire6 l, winding of. the device EPV, wire 65, to the minus bus. It isthus seen that the brake control device EPV is maintained'energized solongas the shoe 20 is raised irrespective of the energized conditions ofthe relays CA and CL. Under this 7 condition with the shoe 20 riding onthe-ramp TR under caution traffic conditions, pulsating current may'flowfrom the secondary 1 windingof transformer 27 through' wire 68,

shoeQO, ramp 'TR,-wire 69, back contact 6 of the repeater relay-RR, wire7 0, contact 10 of the trackrelay T, wire 71, rectifier 8, wire 72,semaphore contact 9., wires 73 and 74, back contact 7 of the relay RR,wire 75, track rails 1', wheels and axle 35, wire 7 6, winding31,'rec'tifier 33, back to the secondary winding of-transformer 27. Itwill be noted that the rectifiers 8 and 33 in the circuit just tracedhave their Valve action poled in the same direction, thus permitting theflow of pulsating current in" the direction in which the circuit wastraced. Also, it is understood that thecircuitjust traced is of ratherlow resistance and of rather high inductance, so

that a-comparatively'large pulsating current will flow, this-pulsatingcurrent lagging considerably behind the voltage of the secondary windingby-reason ofthe inductive characteristic-of the circuit just traced.There is, 110wever', another circuit present, while the shoe 20 is onthe caution ramp, which other circuit is exactly the same as the onejust traced except that it includes the branch of the main relay MRincluding the winding 30 and the rectifier32-in series, instead of thebranch including winding 31 and rectifier 33. This latter'circuit,itwill be noted, has its recti stantially in phase with the voltageoftrans former 27. With a small amountof alternating current of unitypower factor flowing in the coil 30 of the main relay and acomparatively large lagging pulsatmg current flowing in the otherwinding thereof, a torque isproduced in the rotor of the relay MR; thiscauses the contact 80 to be moved to the left hand position to completethe following pick-up circuit for the caution relay CA, this cautionlrelay as well-as the clear relay CL both having assumed theirde-energized position in response to lifting of the? 1 shoe 20, becausethe stick circuits for both of these relays were then opened by openingthe shoe contact 21 :beginning at the plus bus, wire 81, shoe contact23, wire 82, polar contact 80-of the main relay MR, assuming its lefthand position, wire, 83,-winding of the caution relay CA, wires 43 and4:4 to the minus bus. As the shoe 20 moves off the track ramp" TR thestick circuit for: the caution relay CA, and including the normallyclosed shoe contacts 21, heretofore'tracedis again closed thusmaintaining the caution relay CA energized. f

' l/Viththe caution-relay CA energized andthe-clear relay CLole-energized, theishoe 20 having leftthe track ramp; TR, theelectropneumatic valve EPV is lie-energized, be-

cause the contact 60 of the clear relay CL is now in its de-energiz'edposition, thereby; sounding the whistle W, to advise the engineer'thathewill obtaina brake application unless he operates his annulling pushbutton- AN. The circuit for the whistle valve may be traced as follows:beginning at the plus bus, wires 52 and 53, contact 54, wires 55 and56, contact 22, wire 57 contact 58, wire 59, contact 60 of the clearrelay CL in its lower position, wire 84, winding of whistle valve W,wire 85 to the minus bus. f r i Theengineer may nowiby depressing hispush button AN pick up-the clearrelay CL and re-energize the brakecontrol device EPV beforethe brakes are actually fully applied, byclosing the following circuit :beginning at the-plus bus, wire 36,contacts 21, wires 37,

'38, 46, and 87, contacts 88 of the push button- AN, wires 89, 90 and50, lower windingof the clear relay'CL, wires 51 and 44, to the negativebus. As soon as the clear relay CL has assumed its energizedposition,its stick circuit heretofore traced. is closed, thusmaintaming th srelayenergized, and 1f theengi neer then moves his annulling push buttonto itsnormal position before the contact 63 has had an opportunity-toopen, this contact. 631' being a time-controlled 1 contact which opensif the annu'lling' push button AN is depressed, for say more than 15seconds, the device EPV will again be energized through the circuitheretoforetracedf Letus now assume that the railway vehicle in question,equipped with'the-car-carried ap paratus embody ng the presentinvention, passes a? danger ramp (a ramp entirely dis connectedfromthe'track rails) under which condition the caution relay CA and theclear relay'CL' will'again be de-energized for reasonsheretofore given,the device EPV being maint'ained'energized so long as the shoe 20 is Ilifted. Since, under this condition, the main relay MR'will' not beenergized by current of 11;

any kind, because the circuit including the rainp and main relay MRisno-w open at the contact. TOOf the track relay T, neither the relay CAnor the relay CL will be energized.

Asthe shoe 20leaves the ramp during passage of. that vehicle by suchramp the temporary circuit including shoe contacts 24 for the device EPVis broken, and the device EPV will assume its tie-energized position andeffeet a brake application. alert and decides. it to be safe to allowthe train to again proceed before comingto a full If the engineer isstop, he maydepress the reset push button RS not convenientlyaccessible, but accessible to the engineer only after a certain amountof annoyance and inconvenience.

Such depression of the reset push button RS effects shunting of thestick contact 40 of caution relay. CA by the contact 92 of the resetpush button and also the shunting of the stick contact 48 of the clearrelay CL by closure of the contact 93 of the reset push button-BS, sothat the caution relay CA and the clear relay CL will assume theirenergized position, and thereafter remain energized through the stickcircuits heretofore traced. If the engineer immediately returns hisreset push button RS to normal it will efiect closure of the contact 54thereof, thereby re energizing the device EPV through the circuit forthis device heretofore traced. Attention is particularly directed to thefact that de-energization of the device EPV under danger trafiicconditions, as just explained, does not effect sounding of an audiblesignal, so that the engineer must actually be on the alert to avoid 'abrake application under clanger trafiic conditions, whereasde-energization of the'device EPV under caution traffic conditions asheretofore explained is accompan ied bv the sounding of the whistle W,and reenergization of the device EPV may be-obtained by depressing thepush button AN lo cated conveniently to the engineer.

Let us now assume that the Vehicle passes a track ramp under cleartrafiic conditions,

it being assumed that the car-carried apparatus is also in its normalclear traflic condltion prior to such passage. As the shoe 20 rides upthe incline of the ramp, the shoe contacts 21 and 22 are opened and theshoe contacts 23 and 24 are closed, so that the caution relay CA and theclear relay CL are de-energized, but the device EPV is maintainedenergized temporarily through the auxiliary circuit including the shoecontact 24. With the shoe 20 engaging the clear ramp TR pulsatingcurrent in appreciable quantity may flow through the winding 30 of themain relay MR through the following circuit and inthe direction saidcircuit is traced :-beginning at the secondary windingof-transformer 27,rectifier 32, winding 30 of the main relay MR,

wire 76, wheels and axle 35, track rails 1, wire 7 5, contact 7 of therepeater relay RR in its raised position, wire 70, contact 10 of thetrack relay T, wire 71, rectifier 8, wire 7 2, semaphore contact 9,wires 7 3 and-95, con-- tact 6 of relay HR in its raised position, wire69,,ramp TR, shoe 20, wire 68, back to the secondary winding oftransformer 27 For reasons heretofore given the pulsating current in thecircuit just traced will be of appreciable value and Will lag behind thevoltage inducing it, by reason of the inductance characteristic of thecircuit. Also, for reain one direction as much as it does in the other,so that a-small alternating current substantially in phase with thevoltage producing it flows in this second circuit.

NVith alternating current of substantially unity power factor flowing inthe coil 31 of the relay MR and with the flow of pulsating currentlagging appreciably behind the voltage producin it flowing in the coil30 of the main relay M a torque will be produced in the rotor of saidrelay MR tending to operate the contact to its right hand position. Thismovement of contact 80 closesthe following pick-up circuit for thecaution relay CA and the clear relay CL beginning at the plus bus, wire81, shoe contacts 23, wire 82,

polar contact 80 of the main relay MB to the right, wire 97, upperwinding of the caution relay CA, wire 98,upper-winding of the clearrelay CL, wire 99, upper winding of the signal relay SR, Wire 100, tothe minus bus. With this circuit completed the relays CA, CL and SR willall assume their energized position. The relays CA and CL will, as soonas the shoe 20 leaves the ramp TR, have their.

stick circuits heretofore traced again completed, so as to maintain themenergized thereafter.

With the relays CA and CL energized and the shoe 2O ret-urnedto itsnormal position the brake control device EPV is again energized, and byreason of the slow-acting characteristic of the device EPV and the factthat this devce is energized so long as the shoe 20 is in its raisedposition, its valve will not actually be opened when a train passes aclear ramp; In this connection, if desired, the Shoe contacts 21-23 and222tmay be of the ficiently long period of time to properly adbyolo-se-circuting the same upon the relay SR assuming its-energizedposition, through the medium of the front contact 103. In other words,the signal relay SR is very quick to pick up, but isvery slow to drop,because the slug 102 is'effectiveto retard a change of flux thereinbetween the time of deenergization of the relay SR and its actual drop-Attention is particularly directed to certain advantages afforded by thesystem em bodying the presentinvention, In the first V, lay MR.Obviously, if an open circuit should .place attention i'sdirected' tothe fact that no wayside source of current srequired for en-.ergizingtheramps TR asis true of certain ramp systems. 'In other words,instead of applying a source of current of 'one polarity or theotlierbetween the track rail and the track ramp, a rectifier is appliedtherebetween, with its valve poled in one direction or the other, thisrectifier requiring no particular attention and having an extremely longlife. Attention is also. directed to the fact that should the rectifierlocated at a pars ticular track location be short-circuited, for somereason or other, this could not pos- .sibly give a false indication onthe car, be

cause the current flow in both windings of the main relay MR would inthat instant flow .in circuits having the same inductance charf Vacteristics, so that the current flowing in these windings would produceno torque in the re-' occur in the ramp circuit, such asthe breaking ofw res 69 or 75, a ClfitIlgGI HldlCltlOIl would be manifested on the tran, which, al-

I though wrong, would be on the side of safety andiwould notbe asundesirable as a false clear, or false caution 1nd1cat1on.- Further,

should an open circuit appear in one of the multiple paths includingwindings 30 and 31,

7 current would flow only in one of these windings and no torque wouldbe produced. The system disclosed is one embodying every possiblefeature of safety, namely, that. all signals function on the side ofsafetyand if they produce a false control or indication due to Y afailure, such control or indicationmanifests danger, thereby stoppingthe train unnecessarily rather than letting it proceed due to suchfailure.

' The rectifiers 8, 8 32 and 33 are preferably vrectifiers of theelectrolytic, crystal or copper oxide type in which the rectifyingaotionis inherent in the structure of the device. Rectifiers of thevacuum gap thermal 7 type may also befuse'd if desired','especiallyifthey do not require external heating of one oftheir electrodes. Therectifiers used shall permit a certain aniount'ofbaokflow, that is, f

leakage in the-opposite direction to thevalve action, thisin order toobtain the alternating current of substantially unity power factorheretofore mentioned; The relay MR should be one of the'two-elementinduction type, and one which will not produce any torque if the currentflow in its two'windings is exactly in phase, and is preferably one inwhich the magneticstructure for'both windings is the sameso thateachwinding associated therewith has the'same inductance as the otherwinding. c

- Having thus shown and described one rather specific embodiment of thepresent invention, it is desired to be understood that the specificapparatus and circuit arrangement selected to illustrate the inventionhas been selected for the purpose of facilitating disclosure of thenature of the invention rather than its scope or the exactconsti-uctionpreferably employed in practicing the same, and this particular "showingis not intended to exhaust all possible embodiments thereof, and it isto be understood that vari- 1 plied, all without departing vfrom thespirit or scope of theinvention or the idea of means underlyingthef-sanie. For instance, the in vention may be applied to'arailwaysystem .of the manual 'block'type, in which event there willbe'sub'stituted for. the pole changing contacts (Sand 7, a pole changingswitch manually operable by the-.towerman; Also, if desired, the presentinvention may be ap plied to systems which set up specific speed limitsinstead of effecting a brake applica-' tion which may be'annulled by theengineer, or if desired, the invention maybe usedfor transmitting twokinds of traflic condition such as proceed and danger instead of threekinds of traflic conditions, :as illustrated. In other words, thepresentinvention is not to be limited in any sense, except as demandedby the scope'of the following claims.

What I claim as new is 1. -Trackway apparatus 1 for automatic traincontrol'systems' comprising; a contact ramp; a rectifier; and means forat times including said rectifier in a circuit branch connectingsaidramp and the rail of the'railway track to permit the free flow ofcurrent from said rail to'said ramp, and at'other timesfin eluding saidrectifier in said branch to permit the free flow of current from saidramp to said rail. 1 y w 2; In an automatic'traincontrol system;

the combinationwith a railway 'track'and' a V vehicle movable thereon,of means'for communicatlng. control influences from the track tothe'vehicle comprising a circuit including in series a source ofalternating current on the vehicle and'a rectifier on the track.

3.-In"a-n' automatic train control sy'ste'ni;

the combination with a railway track and a vehiclemovable thereon, ofmeans for communicating control influences from the track to the vehiclecomprising; an electro-responsive means on the car; and a circuitincluding in series said el-ectro-responsive means, a source ofalternating current on the car, and a rectifier on the track.

4. In an automatic train control system; the combinationwith a railwaytrack and a vehicle movable thereon, of means for comn'iunicatingcontrol influences from thetrack to the vehicle comprising,electro-responsive -imeans on the vehicle responsive to pulsatingcurrent but not responsive to alternating current, a source ofalternating current connected in series therewith, and means locatedresponsive to pulsating currents of different polarity but notresponsiveto alternating current, a source of alternating currentconnected' in series therewith, and means located alongithe trackwayincluding a rectiner for at times including said rectifier in serieswith said source and'electro-responsive means in a mannerto permitpulsating current to flow through said electro-responsive device in onepaiticulal directlon and at other times con mes Wlth each of Smd wmdmgsm a manner necting said rectifier in series with said source andelectro-responslve means to peri mit the flow of pulsating current inthe opposite direction through said electro-responslve means.

6. In an automatic train control system; the combination with a railwaytrack and a vehicle movable thereon; of means for communicating controlinfluences from said track to said vehicle comprising; vehicle carriedapparatus including an electro-responsive device responsive'only .topulsating current, a

source of alternating current connected in series therewith; traclrwayapparatus including a rectifier and means partly on the track :andpartly on the vehicle for at times conductively connecting saidrectifier in series.

with said source and electro-responsive device.

7. In an automatic train control system;

.the combination with a railway track and a vehiclemovable'thereon; andof means for.

including said coils, a source of alternating current connected inserles with said multiple circuits; trackway apparatus includlng atrackway rectifier; and means partly on the track and partly on the carfor connecting said trackway rectifier in series with said source andsaid coils in multiple.

8. In an automatic train control system; the combination with a railwaytrack and a vehicle movable thereon; and of means for communi atingcontrol influences from the track to the vehicle comprising; vehicle carried apparatus including a polyphase induction type relay having twowindings connected in multiple, a rectifier included in se"f ries witheach of said windings in a manner to permit the free flow of current inone direction in a circuit including said coils in multiple through onecoil and'permit the free flow current in the other direction in suchcircuit through the other coil, a source of alternating currentconnected in series with said multiply arranged windings; trackwayapparatus including a trackway rectifier;

and means partly on the vehicle and partly' on the track for at timesconnecting said trackway rectifier in series with said relay and sourceof current.

9,111 an automatic train control system; the combination with a railwaytrack and vehicle movable thereon; and of means for communicatingcontrol influences from the track to the vehicle comprising; vehiclecarried'apparatus including a polyphase induction'type relay having twowindings connected in multiple, a rectifier included in seto permit thefree flow of current in one direction in a circuit including said coilsin multiple through one 0011 and permlt the free 'fiow of current in theother direction in such circuit through the other coil, a source ofalternating current connected in series with said multiply arrangedwindings; trackway apparatus including a trackway rectifier; an meanspartly on the vehicle and partly on the track for at times connectingsaid trackway rectifier in series with said relay to permit the freeflow of current in one direction through said relay and at other timesconnecting said trackway rectifier in series with said source and relayto permit the free fiow of current in the opposite direction.

10. In an automatic train control system, the combination with arailwaytrack divided into blocks and a vehicle movable thereon; ofcommunicating means including a source of energy on the vehicle forcommunicating clear, caution, and stop traffic conditions sounding anaudible'signal upon each entrance of said vehicle into a clear block,means for applying the brakes in a manner so that the brake applicationmay be annulled by suitable annulling means upon entrance of the traininto a caution block, and means for applying the brakes in a manner sothat such brake application cannot be annulled by said annullingmeansbut can be reset by suitable means after a certain amount of annoyanceupon entrance of the train into a stop block.

11. In an automatic train control system, the combination of a railwaytrack and a Vehicle thereon;'of train controlmeans on the vehicle; asource of energyon the vehicle;

. a circuit including said train control means,

said source, and including part of said railway track; and means alongthe railway track and included in said circuit for changing thecharacter irrespective of Value of the current in said circuit derivedfrom said source inaccordance with traflic conditions in advance of saidvehicle. 7

12'. In an automatic train control system, the combination of a railwaytrack and a vehicle-thereon; of train control means on the vehicle; asource of energy on the vehicle; a circuit 1nclud1ng said train controlmeans,

said source, and including part of said railway track, and means alongthe railway track and included in said circuit for changing thecharacterirrespective of value of the current derived from said source intocurrent of one character or another in accordance with traflicconditions in advance of said vehicle.

13; In an automatic train control system,

the combination of .a railway track and a vehicle thereon; of traincontrol means, on the vehicle; a source of energy on the vehicle; acircuit including said train control means, said source, and includingpart of said railway track; and means along the railway track andincluded in said circuit for either interrupting saidcircuit or changingthe character of the current derived from said source in accordance withtrafiic conditions in advance of said vehicle.

14. In an automatic train control system, the combination of a railwaytrack anda vehicle thereon; of train control means on the vehicle; asource of energy on the vehicle; a circuit including said train controlmeans, said source, and including part of said railway track; and meansalong the railway track and included in said circuit for eitherinterrupting said circuit or changing the character of the currentderived from said source into current of one character or another in"accordance with trafiic conditionsin advance of said vehicle.

In testimony whereof I afiix my signature.

THEODORE BODDE.

